Room temperature ionic liquids (abbreviated to RTIL) are increasingly used in organic synthesis because of their particularly advantageous properties (cf. “Room Temperature Ionic liquids. Solvents for synthesis and catalysis”, T. Welton, Chemical Reviews, 1999, 2071-2083). This is because these are relatively nonvolatile solvents with a low vapor pressure which are compatible with the majority of known chemical reagents, which are thermally stable, which are relatively nonflammable and which can be recycled.
In addition to these applications as reaction solvents, room temperature ionic fluids have numerous advantages for liquid-liquid and liquid-gas extraction. Just like supercritical fluids or fluorinated solvents, these ionic liquids are generally immiscible with volatile organic solvents (abbreviated to VOS) and, because of their very high vapor pressures, they can be separated by direct distillation from the solvents (cf. “Modern Separation techniques for the Efficient Workup in Organic Synthesis”, C. C. Tzschucke et al., Angewandte Chemie, Engl. Int. Ed., 2002, 3964-4000).
It is known in the literature to use these ionic liquids as extraction fluids during the following separation operations:                ionic liquid/other solvent or aqueous phase two-phase extraction (cf. “RT ionic liquids as novel media for clean liquid-liquid extraction”, J. G. Huddleston et al., Chem. Commun., 1998, 1765-1766);        liquid/liquid microextraction using a drop of an ionic liquid coupled to liquid chromatography (cf. “Ionic liquid-based liquid-phase microextraction, a new sample enrichment procedure for liquid chromatography”, J. Liu et al., J. Chromatograph. A, 2004, 1026, 143-147);        separations of gaseous, liquid, sulfur-comprising contaminants in hydrocarbons (cf. documents of patent WO-A-2003/070667 and WO-A-2003/040264);        separation of compounds exhibiting very similar boiling points (cf. document of patent WO-A-2002/074718); and        extraction of heavy metals by complexing agents in ionic liquids (cf. “First application of calixarenes as extractants in room-temperature ionic liquids”, S. Kojiro, Chemistry Letters, 2004, 320-321).        
It should be noted that all these separation operations are targeted at extracting a compound using an extraction fluid composed of an ionic liquid, that is to say and causing this compound to migrate, by material transfer, from the liquid phase to the ionic liquid.
Recently, interest has been taken in functionalized room temperature ionic liquids, also known as task-specific ionic liquids (abbreviated to TSIL in the continuation of the present description), which are particularly well suited to homogeneous-phase supported synthesis. Reference may be made on this subject to the document of patent WO-A-2004/029004.
These functionalized ionic liquids combine the advantages of syntheses in the liquid phase and on a solid support, owing to the fact that they make it possible:                in the liquid phase, to carry out a large number of reactions, to rapidly optimize the operating conditions and to synthesize products in large amounts, and        on a solid support, to rapidly purify by successively washing the solid support in various solvents.        
French patent application No. 04 07623, filed on 8 Jul. 2004 on behalf of the Applicant Company and of the Centre National de la Recherche Scientifique, presents a microfluidic system comprising a microreactor which is composed of a drop comprising at least one functionalized or nonfunctionalized ionic liquid. This microreactor is without walls, the interface of the ionic liquid(s) with the surrounding medium and with the support on which the drop is deposited defining the limits of the microreactor.
This patent application also relates to processes for implementing chemical or biochemical reactions and/or mixtures using this microreactor of drop type, and it mentions the extraction and/or the purification of the product(s) resulting from the reaction carried out in the drop of ionic liquid.